The invention relates to an apparatus, which converts a rotational movement into a back and forth movement and is also referred to as a ball roller spindle.
In German Patent Application No. G 94 00 721.7, an apparatus is described for converting a rotational movement into a back and forth lifting motion or the reverse. The known apparatus has a spindle with at least one guiding groove in an outer surface, a bearing body and a force transfer device with a ball mechanism. The spindle and the bearing body are disposed so that they can be shifted rotationally as well as axially relative to one another. The ball mechanism is mounted in a continuous borehole in the bearing body in such a manner that it protrudes into the guiding groove on one side and, on an opposite side, protrudes towards the outside over the wall section of the bearing body. A ball race is fitted onto the bearing body and supported at the ball mechanism, placing the latter under tension in the direction of the guiding groove. In order to prevent the ball race from being pushed in an axial direction out of a region of the ball mechanism with a result of releasing driving balls of the ball mechanism, either a groove, V-shaped in cross section, is provided in an inner surface of the ball race or the apparatus is only intended for smaller lifts for the known mechanisms for each ball mechanism of the majority of ball mechanisms.
Moreover, an apparatus for controlling valves, robots or tool machines is described in European Patent Application No. EP 0 337 418 A1. For this known apparatus, a ball mechanism is supported in a guiding groove of a spindle and in an axial groove of a housing enclosing the spindle and bearing body. At the same time, the spindle is mounted rotatably in a housing. The known apparatus can be used in a variety of ways to effect relative motions between the spindle, the bearing body and the housing or for equipment produced from these structural elements, such as metering pumps. However, these devices have a comparatively complicated construction and therefore are relatively expensive to manufacture.